1. Field of the Invention
The present invention relates to an improvement of the clamping device for camera lens hoods.
2. Description of the Prior Art
The lens hood is an accessory mounted around the outer periphery of a built-in lens hood which is telescopically mounted on the lens barrel or its outer sleeve in a camera. There are known various methods for mounting the lens hood on the outer sleeve. One of these methods is that the threaded end of the lens hood is engaged by a threaded attachment portion provided on the forward end of the lens barrel to fixedly mount the hood on the lens barrel.
A second method is also known in which the lens hood is mounted over and secured to the outer periphery of the forward end of the lens barrel by means of a screw member which is threadedly engaged in a lateral threaded aperture provided through the sidewall of the lens hood.
One of the clamping devices constructed in accordance with the above second method is disclosed in U.S. Pat. No. 3,384,767. This clamping device comprises a pair of projections extending radially inwardly from the inner periphery of a lens hood at one end and spaced away from each other, a fixing pin member being located on the lens hood at a different place and movable radially relative to the hood, and a spring for biasing the fixing pin member inwardly. The clamping device disclosed in the above U.S. Patent is advantageous in that it has a relatively simple construction so as to facilitate the mounting and removal of the lens hood. Since the hood is fixed to the camera portion by spring biasing the pin member, however, the hood can easily and undesirably fall off the lens barrel if a large force is applied to the side of the hood against the biasing force of the spring when the hood is to be mounted on the lens barrel. When the tips of the projections engage in a V-shaped groove on the forward end of the lens barrel and if the pin member is placed in its outward position, the tip of the pin member may override a collar near the V-shaped groove so that the lens hood will undesirably move inwardly beyond a predetermined setting position to completely cover the rearward portion of the lens barrel.